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1702 Publications visible to you, out of a total of 1702

Abstract

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Author: Friedrich Röpke

Date Published: 1st Jul 2024

Publication Type: InProceedings

Abstract (Expand)

Working with cognate data involves handling synonyms, that is, multiple words that describe the same concept in a language. In the early days of language phylogenetics it was recommended to select one synonym only. However, as we show here, binary character matrices, which are used as input for computational methods, do allow for representing the entire dataset including all synonyms. Here we address the question how one can and if one should include all synonyms or whether it is preferable to select synonyms a priori. To this end, we perform maximum likelihood tree inferences with the widely used RAxML-NG tool and show that it yields plausible trees when all synonyms are used as input. Furthermore, we show that a priori synonym selection can yield topologically substantially different trees and we therefore advise against doing so. To represent cognate data including all synonyms, we introduce two types of character matrices beyond the standard binary ones: probabilistic binary and probabilistic multi-valued character matrices. We further show that it is dataset-dependent for which character matrix type the inferred RAxML-NG tree is topologically closest to the gold standard. We also make available a Python interface for generating all of the above character matrix types for cognate data provided in CLDF format.

Authors: Luise Häuser, Gerhard Jäger, Alexandros Stamatakis

Date Published: 28th Jun 2024

Publication Type: Proceedings

Abstract (Expand)

The Message-Passing Interface (MPI) and C++ form the backbone of high-performance computing and algorithmic research in the field of distributed-memory computing, but MPI only provides C and Fortran bindings. This provides good language interoperability, but higher-level programming languages make development quicker and less error-prone. We propose novel C++ language bindings designed to cover the whole range of abstraction levels from low-level MPI calls to convenient STL-style bindings, where most parameters are inferred from a small subset of the full parameter set. This allows for both rapid prototyping and fine-tuning of distributed code with predictable runtime behavior and memory management. Using template-metaprogramming, only code paths required for computing missing parameters are generated at compile time, which results in (near) zero-overhead bindings.

Authors: Kunal Agrawal, Erez Petrank, Demian Hespe, Lukas Hübner, Florian Kurpicz, Peter Sanders, Matthias Schimek, Daniel Seemaier, Tim Niklas Uhl

Date Published: 17th Jun 2024

Publication Type: Proceedings

Abstract

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Authors: Wei Liu, Stephen Wan, Michael Strube

Date Published: 16th Jun 2024

Publication Type: InProceedings

Abstract

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Authors: Pascal Memmesheimer, Stefan Machmeier, Vincent Heuveline

Date Published: 5th Jun 2024

Publication Type: Journal

Abstract (Expand)

In the analysis of DNA sequencing data for finding disease causing mutations, to understand evolutionary relationships between species, and to find variants, DNA-Reads are compared to a reference genome. A reference genome is a representative example for a set of genes of a species. Sorting these aligned DNA-Reads by their position within the reference sequence is a crucial step in many of these downstream analyses. SAMtools sort, a widely used tool, performs external memory sorting of aligned DNA-Reads stored in the BAM format (Binary Alignment Map). This format allows for compressed storage of alignment data. SAMtools sort provides the most comprehensive set of features while exhibiting demonstrably faster execution times than its open source alternatives. In this work, we analyze SAMtools sort for sorting BAM files and propose methods to reduce its runtime. We divide the analysis into three parts: management of temporary files, compression, and input/output (IO). For the management of temporary files, we find that the maximum number of temporary files SAMtools sort can open concurrently is lower than the maximum number of open files permitted by the operating system. This results in an unnecessarily high number of merges of temporary files into larger temporary files, introducing overhead as SAMtools sort performs extra write and compression operations. To overcome this, we propose a dynamic limit for the number of temporary files, adapting to the operating system’s soft limit for open files. For compression, we test seven different libraries for compatible compression and a range of compression levels, identifying options that offer faster compression and result in a speedup of up to five times in single-threaded execution of SAMtools sort. For IO, we demonstrate that a minimal level of compression avoids IO overhead, thereby reducing the runtime of SAMtools sort compared to uncompressed output. However, we also show that uncompressed output can be used in the pipelining of SAMtools commands to reduce the runtime of subsequent SAMtools commands. Our proposed modifications to SAMtools sort and user behavior have the potential to achieve speedups of up to 6. This represents an important contribution to the field of bioinformatics, considering the widespread adoption of SAMtools sort evidenced by its over 5,000 citations and over 5.1 million downloads through Bioconda.

Authors: Dominik Siebelt, Lukas Hübner, Alexandros Stamatakis

Date Published: 3rd Jun 2024

Publication Type: Bachelor's Thesis

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